1,721,007 research outputs found
A note on a new variant of Murty's ranking assignments algorithm
No full textIn this paper a variant of Murty's algorithm for ranking assignments according to cost is presented. It is shown that the worst-case computational complexity is better in this variant than in the original form of the algorithm. Computational results comparing three methods for ranking assignments are reported. They show that the behaviour of the new variant is also better in practice. © 2003 Springer-Verlag Berlin/Heidelberg
An automated reference point-like approach for multicriteria shortest path problems
No full textIn this paper we introduce a method of analysis for the automated ordering and selection of solutions of a multicriteria shortest path model. The method is based on a reference point approach, where the paths in a specific priority region are ranked by non-decreasing order of a Chebyshev metric. In order to list paths according with this objective function a labelling algorithm is proposed. The developed method is applied in a video-traffic routing context. Computational results are presented and analysed, for randomly generated networks of significant dimension. © Systems Engineering Society of China and Springer 2006
A mixed integer linear formulation for the minimum label spanning tree problem
No full textIn this paper we deal with the minimum label spanning tree problem. This is a relevant problem with applications such as telecommunication networks or electric networks, where each edge is assigned with a label (such as a color) and it is intended to determine a spanning tree with the minimum number of different labels. We introduce some mixed integer formulations for this problem and prove that one of their relaxations always gives the optimal value. Finally we present and discuss the results of computational experiments. © 2009 Elsevier Ltd. All rights reserved
Bicriteria path problem minimizing the cost and minimizing the number of labels
No full textWe address a bicriterion path problem where each arc is assigned with a cost value and a label (such as a color). The first criterion intends to minimize the total cost of the path (the summation of its arc costs), while the second intends to get the solution with a minimal number of different labels. Since these criteria, in general, are conflicting criteria we develop an algorithm to generate the set of non-dominated paths. Computational experiments are presented and results are discussed. © 2013 Springer-Verlag Berlin Heidelberg
An algorithm for ranking quickest simple paths
No full textIn this paper, an algorithm for ranking loopless paths in undirected networks, according to the transmission time, is presented. It is shown that the worst-case computational time complexity of the algorithm presented is script O sign (Kr(m+nlogn)), which is also the best-known complexity to solve this problem. The worst-case memory complexity is script O signs (Kn), which improves the existing algorithms. Finally, comparative computational results, with other algorithms for the same problem, are reported. © 2003 Elsevier Ltd. All rights reserved
A comprehensive survey on the quickest path problem
No full textThis work is a survey on a special minsum-maxmin bicriteria problem, known as the quickest path problem, that can model the transmission of data between two nodes of a network. Moreover, the authors review the problems of ranking the K quickest paths, and the K quickest loopless paths, and compare them in terms of the worst-case complexity order. The classification presented led to the proposal of a new variant of a known K quickest loopless paths algorithm. Finally, applications of quickest path algorithms are mentioned, as well as some comparative empirical results. © Springer Science+Business Media, LLC 2006
A Bicriterion Approach for Routing Problems in Multimedia Networks
No full textRouting problems in communication networks supporting multiple services, namely, multimedia applications, involve the selection of paths satisfying multiple constraints (of a technical nature) and seeking simultaneously to "optimize" the associated metrics. Although traditional models in this area are single-objective, in many situations, it is important to consider different, eventually conflicting, objectives. In this paper, we consider a bicriterion model dedicated to calculating nondominated paths for specific traffic flows (associated with video services) in multiset-vice high-speed networks. The mathematical formulation of the problem and the bicriterion algorithmic approach developed for its resolution are presented together with computational tests regarding an application to video-traffic routing in a high-speed network. The algorithmic approach is an adaptation of recent work by Ernesto Martins and his collaborators, namely, the MPS algorithm. © 2003 Wiley Periodicals, Inc
On the bicriterion - minimal cost/minimal label - spanning tree problem
No full textWe address a bicriterion spanning tree problem relevant in some application fields such as telecommunication networks or transportation networks. Each edge is assigned with a cost value and a label (such as a color). The first criterion intends to minimize the total cost of the spanning tree (the summation of its edge costs), while the second intends to get the solution with a minimal number of different labels. Since these criteria, in general, are conflicting criteria we developed an algorithm to generate the set of non-dominated spanning trees. Computational experiments are presented and results discussed. © 2009 Elsevier B.V. All rights reserved
An approach to determine unsupported non-dominated solutions in bicriteria integer linear programs
No full textIn this paper, we introduce a method for finding both supported and unsupported non-dominated solutions of a bicriteria integer linear program (BCILP). One-phase and two-phase implementations of the method are described, and their interactive versions are outlined. The one-phase method and the second phase of the other are based on the minimization of weighted Chebyshev distances to well-chosen reference points. The dynamic change of reference point proposed here makes this method particularly suitable for interactive approaches. Computational experiments on random instances of three classes of BCILP are reported and discussed. The implementation of the proposed method as a method to approximate the set of non-dominated solutions is described and evaluated in computational terms
An exact lexicographic approach for the maximally risk-disjoint/minimal cost path pair problem in telecommunication networks
Full text linkThe paper addresses the lexicographically maximal risk-disjoint/minimal cost path pair problem that aims at finding a pair of paths between two given nodes, which is the shortest (in terms of cost) among those that have the fewest risks in common. This problem is of particular importance in telecommunication network design, namely concerning resilient routing models where both a primary and a backup path have to be calculated to minimize the risk of failure of a connection between origin and terminal nodes, in case of failure along the primary path and where bandwidth routing costs should also be minimized. An exact combinatorial algorithm is proposed for solving this problem which combines a path ranking method and a path labelling algorithm. Also an integer linear programming (ILP) formulation is shown for comparison purposes. After a theoretical justification of the algorithm foundations, this is described and tested, together with the ILP procedure, for a set of reference networks in telecommunications, considering randomly generated risks, associated with Shared Risk Link Groups (SRLGs) and arc costs. Both methods were capable of solving the problem instances in relatively short times and, in general, the proposed algorithm was clearly faster than the ILP formulation excepting for the networks with the greatest dimension and connectivity
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